Microbiology

Mechanism of Action:

The mechanism of action of ciclopirox has been investigated using various in vitro and in vivo infection models. One in vitro study suggested that ciclopirox acts by chelation of polyvalent cations (Fe+3 or Al+3) resulting in the inhibition of the metal-dependent enzymes that are responsible for the degradation of peroxides within the fungal cell. The clinical significance of this observation is not known.

In vitro methodologies employing various broth or solid media with and without additional nutrients have been utilized to determine ciclopirox minimum inhibitory concentration (MIC) values for the dermatophytic molds. (1-2) As a consequence, a broad range of MIC values, 1-20 mcg/mL were obtained for Trichophyton rubrum and Trichophyton mentagrophytes species. Correlation between in vitro MIC results and clinical outcome has yet to be established for ciclopirox.

One ex vivo study was conducted evaluating 8% ciclopirox against new and established Trichophyton rubrum and Trichophyton mentagrophytes infections in ovine hoof material. (3) After 10 days of treatment the growth of T. rubrum and T. mentagrophytes in the established infection model was very minimally affected. Elimination of the molds from hoof material was not achieved in either the new or established infection models.

In vitro susceptibility testing methods for determining ciclopirox MIC values against dermatophytic molds, including Trichophyton rubrum species, have not been standardized or validated. Ciclopirox MIC values will vary depending on the susceptibility testing method employed, composition and pH of media and the utilization of nutritional supplements. Breakpoints to determine whether clinical isolates of Trichophyton rubrum are susceptible or resistant to ciclopirox have not been established.

Studies have not been conducted to evaluate drug resistance development in T. rubrum species exposed to 8% ciclopirox topical solution. Studies assessing cross-resistance to ciclopirox and other known antifungal agents have not been performed.

No studies have been conducted to determine whether ciclopirox might reduce the effectiveness of systemic antifungal agents for onychomycosis. Therefore, the concomitant use of 8% ciclopirox topical solution and systemic antifungal agents for onychomycosis is not recommended.

As demonstrated in pharmacokinetic studies in animals and man, ciclopirox olamine is rapidly absorbed after oral administration and completely eliminated in all species via feces and urine. Most of the compound is excreted either unchanged or as glucuronide. After oral administration of 10 mg of radio labeled drug (14C- ciclopirox) to healthy volunteers, approximately 96% of the radioactivity was excreted renally within 12 hours of administration. Ninety four percent of the renally excreted radioactivity was in the form of glucuronides. Thus, glucuronidation is the main metabolic pathway of this compound.

Systemic absorption of ciclopirox was determined in 5 patients with dermatophytic onychomycoses, after application of Ciclopirox Topical Solution, 8% (Nail Lacquer) to all 20 digits and adjacent 5 mm of skin once daily for six months. Random serum concentrations and 24 hour urinary excretion of ciclopirox were determined at two weeks and at 1, 2, 4 and 6 months after initiation of treatment and 4 weeks post-treatment. In this study, ciclopirox serum levels ranged from 12-80 ng/mL. Based on urinary data, mean absorption of ciclopirox from the dosage form was <5% of the applied dose. One month after cessation of treatment, serum and urine levels of ciclopirox were below the limit of detection.

In two vehicle-controlled trials, patients applied Ciclopirox Topical Solution, 8% (Nail Lacquer) to all toenails and affected fingernails. Out of a total of 66 randomly selected patients on active treatment, 24 had detectable serum ciclopirox concentrations at some point during the dosing interval (range 10.0-24.6 ng/mL). It should be noted that eleven of these 24 patients took concomitant medication containing ciclopirox as ciclopirox olamine cream 0.77%.

The penetration of the Ciclopirox Topical Solution, 8% (Nail Lacquer) was evaluated in an in vitro investigation. Radiolabeled ciclopirox applied once to onychomycotic toenails that were avulsed demonstrated penetration up to a depth of approximately 0.4 mm. As expected, nail plate concentrations decreased as a function of nail depth. The clinical significance of these findings in nail plates is unknown. Nail bed concentrations were not determined.

(To understand fully the indication for this product, please read the entire INDICATIONS AND USAGE section of the labeling.)

Ciclopirox Topical Solution, 8% (Nail Lacquer), as a component of a comprehensive management program, is indicated as topical treatment in immunocompetent patients with mild to moderate onychomycosis of fingernails and toenails without lunula involvement, due to Trichophyton rubrum. The comprehensive management program includes removal of the unattached, infected nails as frequently as monthly, by a health care professional who has special competence in the diagnosis and treatment of nail disorders, including minor nail procedures.

No studies have been conducted to determine whether ciclopirox might reduce the effectiveness of systemic antifungal agents for onychomycosis. Therefore, the concomitant use of 8% ciclopirox topical solution and systemic antifungal agents for onychomycosis is not recommended.

Ciclopirox Topical Solution, 8% (Nail Lacquer) should be used only under medical supervision as described above.

The effectiveness and safety of Ciclopirox Topical Solution, 8% (Nail Lacquer) in the following populations has not been studied. The clinical trials with use of Ciclopirox Topical Solution, 8% (Nail Lacquer) excluded patients who: were pregnant or nursing, planned to become pregnant, had a history of immunosuppression (e.g., extensive, persistent, or unusual distribution of dermatomycoses, extensive seborrheic dermatitis, recent or recurring herpes zoster, or persistent herpes simplex), were HIV seropositive, received organ transplant, required medication to control epilepsy, were insulin dependent diabetics or had diabetic neuropathy. Patients with severe plantar (moccasin) tinea pedis were also excluded.

The safety and efficacy of using Ciclopirox Topical Solution, 8% (Nail Lacquer) daily for greater than 48 weeks have not been established.

The results of use of Ciclopirox Topical Solution, 8% (Nail Lacquer) in treatment of onychomycosis of the toenail without lunula involvement were obtained from two double-blind, placebo-controlled studies conducted in the US. In these studies, patients with onychomycosis of the great toenails without lunula involvement were treated with Ciclopirox Topical Solution, 8% (Nail Lacquer) in conjunction with monthly removal of the unattached, infected toenail by the investigator. Ciclopirox Topical Solution, 8% (Nail Lacquer) was applied for 48 weeks. At baseline, patients had 20-65% involvement of the target great toenail plate. Statistical significance was demonstrated in one of two studies for the endpoint “complete cure” (clear nail and negative mycology), and in two studies for the endpoint “almost clear” (≤10% nail involvement and negative mycology) at the end of study. These results are presented below.

The summary of reported patient outcomes for the ITT population at 12 weeks following the end of treatment is presented below. Note that post-treatment efficacy assessments were scheduled only for patients who achieved a complete cure.

If a reaction suggesting sensitivity or chemical irritation should occur with the use of Ciclopirox Topical Solution, 8% (Nail Lacquer) treatment should be discontinued and appropriate therapy instituted.

So far there is no relevant clinical experience with patients with insulin dependent diabetes or who have diabetic neuropathy. The risk of removal of the unattached, infected nail, by the health care professional and trimming by the patient should be carefully considered before prescribing to patients with a history of insulin dependent diabetes mellitus or diabetic neuropathy.

Patients should have detailed instruction regarding the use of Ciclopirox Topical Solution, 8% (Nail Lacquer) as a component of a comprehensive management program for onychomycosis in order to achieve maximum benefit with the use of this product.

The patient should be told to:

Use Ciclopirox Topical Solution, 8% (Nail Lacquer) as directed by a health care professional. Avoid contact with eyes and mucous membranes. Contact with skin other than skin immediately surrounding the treated nail(s) should be avoided. Ciclopirox Topical Solution, 8% (Nail Lacquer) is for external use only.

Ciclopirox Topical Solution, 8% (Nail Lacquer) should be applied evenly over the entire nail plate and 5 mm of surrounding skin. If possible, Ciclopirox Topical Solution, 8% (Nail Lacquer) should be applied to the nail bed, hyponychium, and the under surface of the nail plate when it is free of the nail bed (e.g., onycholysis). Contact with the surrounding skin may produce mild, transient irritation (redness).

Removal of the unattached, infected nail, as frequently as monthly, by a health care professional is needed with use of this medication. Inform a health care professional if you have diabetes or problems with numbness in your toes or fingers for consideration of the appropriate nail management program.

Inform a health care professional if the area of application shows signs of increased irritation (redness, itching, burning, blistering, swelling, oozing).

Up to 48 weeks of daily applications with Ciclopirox Topical Solution, 8% (Nail Lacquer) and professional removal of the unattached, infected nail, as frequently as monthly, are considered the full treatment needed to achieve a clear or almost clear nail (defined as 10% or less residual nail involvement).

Six months of therapy with professional removal of the unattached, infected nail may be required before initial improvement of symptoms is noticed.

A completely clear nail may not be achieved with use of this medication. In clinical studies less than 12% of patients were able to achieve either a completely clear or almost clear toenail.

Do not use the medication for any disorder other than that for which it is prescribed.

Do not use nail polish or other nail cosmetic products on the treated nails.

No carcinogenicity study was conducted with Ciclopirox Topical Solution, 8% (Nail Lacquer), formulation. A carcinogenicity study of ciclopirox (1% and 5% solutions in polyethylene glycol 400) in female mice dosed topically twice per week for 50 weeks followed by a 6-month drug-free observation period prior to necropsy revealed no evidence of tumors at the application sites.

In human systemic tolerability studies following daily application (~340 mg of Ciclopirox Topical Solution, 8% (Nail Lacquer)) in subjects with distal subungual onychomycosis, the average maximal serum level of ciclopirox was 31±28 ng/mL after two months of once daily applications. This level was 159 times lower than the lowest toxic dose and 115 times lower than the highest nontoxic dose in rats and dogs fed 7.7 and 23.1 mg ciclopirox (as ciclopirox olamine)/kg/day.

The following in vitro genotoxicity tests were conducted with Ciclopirox Topical Solution, 8% (Nail Lacquer): Ames Salmonella test (negative); unscheduled DNA synthesis in the rat hepatocytes (negative); cell transformation assay in BALB/c3T3 cell assay (positive). The positive response of the lacquer formulation in the BALB/c3T3 test was attributed to its butyl monoester of poly[methylvinyl ether/maleic acid] resin component (Gantrez® ES-435), which also tested positive in this test. The cell transformation assay may have been confounded because of the film forming nature of the resin. Gantrez® ES-435 tested nonmutagenic in both the in vitro mouse lymphoma forward mutation assay with or without activation and unscheduled DNA synthesis assay in rat hepatocytes.

Oral reproduction studies in rats at doses up to 3.85 mg ciclopirox (as ciclopirox olamine)/kg/day [equivalent to approximately 1.4 times the potential exposure at the maximum recommended human topical dose (MRHTD)] did not reveal any specific effects on fertility or other reproductive parameters. MRHTD (mg/m2) is based on the assumption of 100% systemic absorption of 27.12 mg ciclopirox (~340 mg Ciclopirox Topical Solution, 8% ((Nail Lacquer)) that will cover all the fingernails and toenails including 5 mm proximal and lateral fold area plus onycholysis to a maximal extent of 50%.

Teratology studies in mice, rats, rabbits, and monkeys at oral doses of up to 77, 23, 23 or 38.5 mg, respectively, of ciclopirox as ciclopirox olamine/kg/day (14, 8, 17, and 28 times MRHTD), or in rats and rabbits receiving topical doses of up to 92.4 and 77 mg/kg/day, respectively (33 and 55 times MRHTD), did not indicate any significant fetal malformations.

There are no adequate or well controlled studies of topically applied ciclopirox in pregnant women. Ciclopirox Topical Solution, 8% (Nail Lacquer) should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

It is not known whether this drug is excreted in human milk. Since many drugs are excreted in human milk, caution should be exercised when Ciclopirox Topical Solution, 8% (Nail Lacquer) is administered to a nursing woman.

Based on the safety profile in adults, Ciclopirox Topical Solution, 8% (Nail Lacquer) is considered safe for use in children twelve years and older. No clinical trials have been conducted in the pediatric population.

Clinical studies of Ciclopirox Topical Solution, 8% (Nail Lacquer) did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between elderly and younger patients.

In the vehicle-controlled clinical trials conducted in the US, 9% (30/327) of patients treated with Ciclopirox Topical Solution, 8% (Nail Lacquer) and 7% (23/328) of patients treated with vehicle reported treatment-emergent adverse events (TEAE) considered by the investigator to be causally related to the test material. The incidence of these adverse events, within each body system, was similar between the treatment groups except for Skin and Appendages: 8% (27/327) and 4% (14/328) of subjects in the ciclopirox and vehicle groups reported at least one adverse event, respectively. The most common were rash-related adverse events: periungual erythema and erythema of the proximal nail fold were reported more frequently in patients treated with Ciclopirox Topical Solution, 8% (Nail Lacquer) (5% [16/327]) than in patients treated with vehicle (1% [3/328]). Other TEAEs thought to be causally related included nail disorders such as shape change, irritation, ingrown toenail, and discoloration. The incidence of nail disorders was similar between the treatment groups (2% [6/327] in the Ciclopirox Topical Solution, 8% (Nail Lacquer) group and 2% [7/328] in the vehicle group). Moreover, application site reactions and/or burning of the skin occurred in 1% of patients treated with Ciclopirox Topical Solution, 8% (Nail Lacquer) (3/327) and vehicle (4/328).

A 21-Day Cumulative Irritancy study was conducted under conditions of semi-occlusion. Mild reactions were seen in 46% of patients with the Ciclopirox Topical Solution, 8% (Nail Lacquer), 32% with the vehicle and 2% with the negative control, but all were reactions of mild transient erythema. There was no evidence of allergic contact sensitization for either the Ciclopirox Topical Solution, 8% (Nail Lacquer), or the vehicle base. In a separate study of the photosensitization potential of Ciclopirox Topical Solution, 8% (Nail Lacquer) in a maximized test design that included the occluded application of sodium lauryl sulfate, no photoallergic reactions were noted. In four subjects localized allergic contact reactions were observed. In the vehicle-controlled studies, one patient treated with Ciclopirox Topical Solution, 8% (Nail Lacquer) discontinued treatment due to a rash, localized to the palm (causal relation to test material undetermined).

Use of Ciclopirox Topical Solution, 8% (Nail Lacquer) for 48 additional weeks was evaluated in an open-label extension study conducted in patients previously treated in the vehicle-controlled studies. Three percent (9/281) of subjects treated with Ciclopirox Topical Solution, 8% (Nail Lacquer) experienced at least one TEAE that the investigator thought was causally related to the test material. Mild rash in the form of periungual erythema (1% [2/281]) and nail disorders (1% [4/281]) were the most frequently reported. Four patients discontinued because of TEAEs. Two of the four had events considered to be related to test material: one patient’s great toenail “broke away” and another had an elevated creatine phosphokinase level on Day 1 (after 48 weeks of treatment with vehicle in the previous vehicle-controlled study).

Ciclopirox Topical Solution, 8% (Nail Lacquer) should be used as a component of a comprehensive management program for onychomycosis. Removal of the unattached, infected nail, as frequently as monthly, by a health care professional, weekly trimming by the patient, and daily application of the medication are all integral parts of this therapy. Careful consideration of the appropriate nail management program should be given to patients with diabetes (see PRECAUTIONS).

Removal of the unattached, infected nail, as frequently as monthly, trimming of onycholytic nail, and filing of excess horny material should be performed by professionals trained in treatment of nail disorders.

Patients should file away (with emery board) loose nail material and trim nails, as required, or as directed by the health care professional, every seven days after Ciclopirox Topical Solution, 8% (Nail Lacquer) is removed with alcohol. Ciclopirox Topical Solution, 8% (Nail Lacquer) should be applied once daily (preferably at bedtime or eight hours before washing) to all affected nails with the applicator brush provided. Ciclopirox Topical Solution, 8% (Nail Lacquer) should be applied evenly over the entire nail plate.

If possible, Ciclopirox Topical Solution, 8% (Nail Lacquer) should be applied to the nail bed, hyponychium, and the under surface of the nail plate when it is free of the nail bed (e.g., onycholysis).

Ciclopirox Topical Solution, 8% (Nail Lacquer) should not be removed on a daily basis. Daily applications should be made over the previous coat and removed with alcohol every seven days. This cycle should be repeated throughout the duration of therapy.

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